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Kamis, 04 Juni 2009

Starch Definition

Starch in the plant network has a form of granule (grains) that is different. Microscope with the type of starch may be due to have a shape, size, location hilum is unique, and also the nature birefringent. When added to raw starch in cold water, starch ganule will absorb water and swell. However, the amount of water and be merged swelling limited. Be merged in the water only reaches 30% water content. Increasing the volume of starch granula going in the water at a temperature of 55oC-65oC is indeed the swelling, and swelling after this starch granula will be back on its original. Granula starch can be made tumefy extraordinary, but can not return to the original condition. These changes are called gelatinization. (Winarno, 1987)


Starch in the plant network has a form of granule (grains) that is different. Amilosa show molecular shape heliks (spiral) that can trap molecules-molecules such as in other acid-fatty acid and other forms of hydrocarbons. Granule starch is generally not soluble in cold water but cold water can absorb between 9.1% to 22.7%. Increasing the volume of starch granule going in the water at a temperature of between 55oC to 65oC is indeed the swelling, and after this starch granule can return to the original condition. If the temperature continues to be the granule starch molecules to vibrate so that the bond between the starch molecules and binding of water with the hydrogen bond. If heating is continued with a higher temperature until swelling starch granula a maximum, and then broken, so that at the time of the occurrence of starch gelatinization. (Deshaliman.2003)


The formation of gel is influenced by the concentration of starch because gelatinization also depends on the thickness solution. The viscous solution, the temperature is increasing slowly until the temperature reached a certain thickness is not increased, sometimes even down. Concentration to make the best solution is a 20% gel, the higher the concentration, the gel that is less thick, and after some time viscosity well decrease. And optimum pH of gel formation in the Ph 4-7. When the pH is too high, the formation of the gel quickly but quickly reached down again, whereas if the pH is too low and slow gel found when heating forwarded, viscosity will be down again. In the pH 4-7 gel formation speed slower than pH 10, but if the heating be continued, viscosity not changed. (Setiadi, and Surya Fitri Nurulhuda. 1993)


REFERENCE :

Deshaliman.2003. Memperkuat Ketahanan Pangan dengan Umbi-umbian. http://www.suarapembaruan.com/News/2005/08/06/index.html. Diakses tanggal 22 Maret 2008

Setiadi, dan Surya Fitri Nurulhuda. 1993. Kentang Varietas dan Pembudidayaan. Kanisius. Yogyakarta

Winarno, F.G. 1987. Ilmu Pangan. UI Press. Jakarta.

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